Weight loss is common among people with cancer. It may be the first visible sign of the disease. In fact, 40% of people say they had unexplained weight loss when they were first diagnosed with cancer. Weight loss associated with cancer may be different than other types of weight loss. Doctors refer to a weight loss syndrome called “cachexia,” which is characterized by increased metabolism, loss of skeletal muscle, fatigue, loss of appetite, and decreased quality of life. Cachexia is very common in patients with incurable cancer.